v0.18.1 panics on startup with certain routing config

[guseggert]

Version

v0.18.1

Config

"Routing": {
    "Methods": {
      "find-peers": {
        "RouterName": "DHTs"
      },
      "find-providers": {
        "RouterName": "DHTsAndIndexers"
      },
      "get-ipns": {
        "RouterName": "DHTs"
      },
      "provide": {
        "RouterName": "DHTs"
      },
      "put-ipns": {
        "RouterName": "DHTs"
      }
    },
    "Routers": {
      "CidContact": {
        "Parameters": {
          "Endpoint": "https://cid.contact"
        },
        "Type": "http"
      },
      "DHTs": {
        "Parameters": {
          "Routers": [
            {
              "IgnoreErrors": false,
              "RouterName": "WanDHT",
              "Timeout": "5m"
            },
            {
              "IgnoreErrors": false,
              "RouterName": "LanDHT",
              "Timeout": "1m"
            }
          ]
        },
        "Type": "parallel"
      },
      "DHTsAndIndexers": {
        "Parameters": {
          "Routers": [
            {
              "IgnoreErrors": true,
              "RouterName": "CidContact",
              "Timeout": "3s"
            },
            {
              "IgnoreErrors": false,
              "RouterName": "DHTs",
              "Timeout": "5m"
            }
          ]
        },
        "Type": "parallel"
      },
      "LanDHT": {
        "Parameters": {
          "AcceleratedDHTClient": false,
          "Mode": "auto",
          "PublicIPNetwork": false
        },
        "Type": "dht"
      },
      "WanDHT": {
        "Parameters": {
          "AcceleratedDHTClient": true,
          "Mode": "auto",
          "PublicIPNetwork": true
        },
        "Type": "dht"
      }
    },
    "Type": "custom"
  },

Description

Kubo panics on preload nodes with the above config:

{"level":"error","ts":"2023-02-23T17:47:01.556Z","logger":"cmds/http","caller":"http/handler.go:94","msg":"a panic has occurred in the commands handler!"}                                                                                                                        
{"level":"error","ts":"2023-02-23T17:47:01.556Z","logger":"cmds/http","caller":"http/handler.go:95","msg":"runtime error: invalid memory address or nil pointer dereference"}                                                                                                     
{"level":"error","ts":"2023-02-23T17:47:01.556Z","logger":"cmds/http","caller":"http/handler.go:96","msg":"stack trace:\ngoroutine 2087244 [running]:\nruntime/debug.Stack()\n\truntime/debug/stack.go:24 +0x65\ngithub.com/ipfs/go-ipfs-cmds/http.(*handler).ServeHTTP.func1()\n\
tgithub.com/ipfs/[email protected]/http/handler.go:96 +0xfa\npanic({0x2395380, 0x399af20})\n\truntime/panic.go:890 +0x262\ngithub.com/ipfs/kubo/core/commands.glob..func50(0xc026e76d90, {0x7f79b1115f08, 0xc026e76e00}, {0x248df80?, 0xc002a89cc0?})\n\tgithub.com/ipfs/kubo/c$
re/commands/dht.go:122 +0x16b\ngithub.com/ipfs/go-ipfs-cmds.(*Command).call(0xc0367d5190?, 0xc026e76d90, {0x7f79b1115f08, 0xc026e76e00}, {0x248df80, 0xc002a89cc0})\n\tgithub.com/ipfs/[email protected]/command.go:189 +0x1ab\ngithub.com/ipfs/go-ipfs-cmds.(*Command).Call(0xc
002a89cc0?, 0xc026e76d90?, {0x7f79b1115f08, 0xc026e76e00}, {0x248df80?, 0xc002a89cc0?})\n\tgithub.com/ipfs/[email protected]/command.go:159 +0x4b\ngithub.com/ipfs/go-ipfs-cmds/http.(*handler).ServeHTTP(0xc0021ee060, {0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tgithub.
com/ipfs/[email protected]/http/handler.go:192 +0xa75\ngithub.com/ipfs/go-ipfs-cmds/http.prefixHandler.ServeHTTP({{0x26827a8?, 0xc049660005?}, {0x2babdc0?, 0xc0021ee060?}}, {0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tgithub.com/ipfs/[email protected]/http/apiprefix
.go:24 +0x142\ngithub.com/rs/cors.(*Cors).Handler.func1({0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tgithub.com/rs/[email protected]/cors.go:219 +0x1bd\nnet/http.HandlerFunc.ServeHTTP(0x70?, {0x7f79b1115df8?, 0xc01ab3e0f0?}, 0xfa21c5?)\n\tnet/http/server.go:2109 +0x2f\nnet/ht
tp.(*ServeMux).ServeHTTP(0xc049641681?, {0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tnet/http/server.go:2487 +0x149\ngithub.com/ipfs/kubo/core/corehttp.CheckVersionOption.func1.1({0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tgithub.com/ipfs/kubo/core/corehttp/command
s.go:188 +0x2d8\nnet/http.HandlerFunc.ServeHTTP(0x7f79b1115df8?, {0x7f79b1115df8?, 0xc01ab3e0f0?}, 0xc04d52f718?)\n\tnet/http/server.go:2109 +0x2f\nnet/http.(*ServeMux).ServeHTTP(0x7f79b1115df8?, {0x7f79b1115df8, 0xc01ab3e0f0}, 0xc021b4b300)\n\tnet/http/server.go:2487 +0x14
9\ngithub.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerResponseSize.func1({0x7f79b1115df8?, 0xc01ab3e0a0?}, 0xc021b4b300)\n\tgithub.com/prometheus/[email protected]/prometheus/promhttp/instrument_server.go:288 +0xc5\nnet/http.HandlerFunc.ServeHTTP(0
xe0a1bf?, {0x7f79b1115df8?, 0xc01ab3e0a0?}, 0xc04d52f8c8?)\n\tnet/http/server.go:2109 +0x2f\ngithub.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerRequestSize.func2({0x7f79b1115df8?, 0xc01ab3e0a0?}, 0xc021b4b300)\n\tgithub.com/prometheus/client_golang@v1.
14.0/prometheus/promhttp/instrument_server.go:249 +0x77\nnet/http.HandlerFunc.ServeHTTP(0xc04d52f900?, {0x7f79b1115df8?, 0xc01ab3e0a0?}, 0x30?)\n\tnet/http/server.go:2109 +0x2f\ngithub.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerDuration.func2({0x7f79b
1115df8, 0xc01ab3e0a0}, 0xc021b4b300)\n\tgithub.com/prometheus/[email protected]/prometheus/promhttp/instrument_server.go:108 +0xbf\nnet/http.HandlerFunc.ServeHTTP(0x2bbe930?, {0x7f79b1115df8?, 0xc01ab3e0a0?}, 0x24f1d40?)\n\tnet/http/server.go:2109 +0x2f\ngithub.com/pro
metheus/client_golang/prometheus/promhttp.InstrumentHandlerCounter.func1({0x2bbe930?, 0xc03e6177a0?}, 0xc021b4b300)\n\tgithub.com/prometheus/[email protected]/prometheus/promhttp/instrument_server.go:146 +0xb8\nnet/http.HandlerFunc.ServeHTTP(0x100c625d8?, {0x2bbe930?, 0
xc03e6177a0?}, 0xf18109?)\n\tnet/http/server.go:2109 +0x2f\nnet/http.(*ServeMux).ServeHTTP(0x0?, {0x2bbe930, 0xc03e6177a0}, 0xc021b4b300)\n\tnet/http/server.go:2487 +0x149\ngithub.com/ipfs/kubo/core/corehttp.makeHandler.func1({0x2bbe930?, 0xc03e6177a0?}, 0x7f79b86b9728?)\n\
tgithub.com/ipfs/kubo/core/corehttp/corehttp.go:54 +0x6b\nnet/http.HandlerFunc.ServeHTTP(0xc049660017?, {0x2bbe930?, 0xc03e6177a0?}, 0xe6c7ce?)\n\tnet/http/server.go:2109 +0x2f\nnet/http.serverHandler.ServeHTTP({0xc03960b950?}, {0x2bbe930, 0xc03e6177a0}, 0xc021b4b300)\n\tne
t/http/server.go:2947 +0x30c\nnet/http.(*conn).serve(0xc04bafa820, {0x2bc0a40, 0xc01b788570})\n\tnet/http/server.go:1991 +0x607\ncreated by net/http.(*Server).Serve\n\tnet/http/server.go:3102 +0x4db\n"} 

For more context: https://github.com/protocol/bifrost-infra/pull/2356

[guseggert]

Basically the ipfs dht query command assumes that Kubo is using a DHT, which is not always the case anymore due to the addition of delegated routing. It also has some special logic to favor the WAN DHT and fall back to the LAN DHT if the WAN DHT doesn't have any peers. When custom routing config is specified, this code has no knowledge of whether the content router is a DHT nor a dual DHT (and thus has no knowledge of the WAN and LAN DHTs). The panic that is happening here is due to this--it is assuming a WAN DHT is present, but it's not because custom routing config has been used.

A quick hack that we can use here is to search around in the config for a content router that supports FindClosestPeers and use the first one we stumble on. I think that would unblock bifrost and most users. It's not much extra effort though to just add "query" as a method to the routing config, which lets users specify which router they want to use for "query". Then the equivalent behavior for the existing "query" function (fall back to LAN if WAN is offline) would be to just query both in parallel using a parallel router, which is usually already configured.

[guseggert]

This also leads to the question of whether to add "query" or "find-closest-peers" to the delegated routing API. That's something we can add later, just mentioning it because I don't think it's been considered for delegated routing yet.

[BigLep]

For anyone watching this issue, this is "P0" since it is blocking the rollout of "HTTP Delegated Routing" https://github.com/protocol/bifrost-infra/issues/2183 .

@guseggert : please update here with next steps as they are known.

[guseggert]

I think the best way to quickly unblock here is to add a new routing type called "autoclient", which is the same as "auto" except it disables DHT servers. This is similar as "dht" and "dhtclient", so we would now have "auto" and "autoclient". Then bifrost would switch to use "autoclient" with Experimental.AcceleratedDHTClient enabled. I think this would meet their requirements, and IIRC this is something that Brave et al would like to use too.

This does not resolve the problem of "custom" routing not working correctly with ipfs dht query and ipfs stats dht. That will require more significant work and is something we need to do, because they are both broken now with Routing.Type=custom, but we can at least unblock bifrost with this and it does not add significant amounts of tech debt.

I have already tested this and it works, I am writing tests now for it.

[guseggert]

#9708

[BigLep]

Thanks @guseggert . A couple of things:

1. I'll let @lidel comment on the utility of this beyond Brave contexts (ideally linking to any issues - I thought we had one but am struggling to find it.)
2. Do we need to open up separate issues around "custom routing not working correctly with ipfs dht query and ipfs stats dht"? I assume there are comments from chore: deprecate remaining dht query command #9690 we should extract?

[guseggert]

There is already one open for ipfs stats dht, we can just use that since it's the same root cause: #9482